Investigation of land subsidence development trend of Mashhad-Chenaran plain using Sentinel-1A radar images and its relationship with groundwater depletion
javad Dowlati
1
(
, Department of Geology, Faculty of Sciences, Ferdowsi Mashhad University, Iran
)
Gholamreaza Lashkaripour
2
(
, Department of Geology, Faculty of Sciences, Ferdowsi Mashhad University, Iran
)
naser hafezi moghaddas
3
(
Professor, Department of Geology, Faculty of Sciences, Ferdowsi Mashhad University, Iran
)
yaser maghsoudi
4
(
Associate professor of Photogrammetry and Remote sensing , Faculty of Geomatic, Khaje Nasir Toosi University
)
Keywords: Groundwater, Radar interferometry, Correlation Coefficient, Mashhad-Chenaran plain, Land subsidence,
Abstract :
Extensive exploitation of groundwater resources in the Mashhad-Chenaran aquifer in the last 50 years (1970-2021) has led to a sharp decline in groundwater levels. Negative effects of subsidence due to the severe development of groundwater resources have occurred in some parts of the plain since the late 1980s and in recent years has covered the entire plain. In this study, subsidence of the entire Mashhad-Chenaran plain has been investigated using Sentinel-1A radar image data between 2014 and 2020 using Small Baseline Subset(SBAS) Interfergrametry method. Examination of subsidence maps shows that there are three subsidence areas including area 1 in the southeast of Mashhad, area 2 in the northwest of Mashhad and area 3 in the northwest of the plain. The maximum annual sitting rate in the two subsidence zones is equal to 19 cm per year and in the two subsidence zones 1 and 3 are 8.9 and 12.1 cm per year, respectively. The results of the time series rate estimated using radar image processing at the location of Golmakan GPS stations and Toos power plant with the actual measured values show the high compliance of these two time series. Adaptation of 30-year groundwater level drop curves and subsidence map shows that the triple subsidence zones correspond to areas with groundwater level drop of more than 30 meters. Also, to investigate the relationship between subsidence and groundwater level drop, correlation coefficients and determination coefficients for each well have been calculated using groundwater level and subsidence data at the location of selected observation wells. Based on the obtained correlation coefficients, the selected wells are divided into two groups with a correlation coefficient of more than 0.8 (75% of wells) and between 0.46 and 0.008, which indicates a good correlation between subsidence rate and groundwater level drop in the most observation wells.
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